The present invention generally relates to installation of components of machinery in a sealing relationship with one another and, more particularly, to apparatus for preventing incorrect installation of the machinery components together without a seal plate or with two seal plates therebetween.
An auxiliary power unit for commercial and military aircraft typically includes a small gas turbine engine coupled to a generator or in some cases a starter generator (however, for purposes of brevity, hereinafter only the term “generator” will be used). The purpose of the auxiliary power unit is to provide electric and pneumatic power for aircraft systems while the aircraft is on the ground and in flight.
The gas turbine engine of a typical auxiliary power unit has three main sections—the power section, the load compressor and the gearbox. The power section is the gas generator portion of the engine, producing all the rotary main shaft power for the auxiliary power unit. The load compressor is generally a main shaft-mounted compressor that provides all pneumatic power for the aircraft. The gearbox transfers power from the main shaft of the engine to the oil-cooled generator for production of electrical power. Within the gearbox, power is also transferred to engine accessories, such as the fuel control unit, the lube module, and the cooling fan.
The generator is fitted to the gas turbine engine of the auxiliary power unit at the gearbox and typically is cooled by oil. The source of this oil is from the auxiliary power unit itself. These are called shared oil systems. In order to provide this supply of oil leak-free to the generator, a seal plate is installed between the gas turbine engine gearbox and the generator. If the seal plate is installed incorrectly, for example the seal plate is missing altogether or two or more seal plates are installed instead of only one, a substantial oil leak will occur, causing extreme damage to the auxiliary power unit due to loss of lubricating/cooling oil.
As can be seen, there is a need for an innovation to prevent incorrect installation of the seal plate between the machinery components of an auxiliary power unit in order to ensure a leak-free condition in the installation.